Spinning rotor for open-end spinning machines

ABSTRACT

A spinning rotor for use at high speeds in open-end spinning machines has a rotor cup having an annular wall portion defining a rotor opening, a bottom wall portion merging with the annular wall portion, and a mounting hub extending exteriorly from the bottom wall portion. A rotor shaft is affixed to the mounting hub coaxially with the rotor cup. The merger of the bottom and annular wall portions of the rotor cup defines a maximum exterior diameter of the rotor and an interior rotor groove. The annular wall portion, the bottom wall portion and the mounting hub are of different cross-sectional thicknesses with the cross-sectional thickness of the bottom wall portion increasing from the rotor groove to the mounting hub. The wall thickness is less than 1.2 mm in the area of the maximum exterior diameter of the rotor cup ( 2 ) and the rotor cup has an aerodynamic exterior contour free of edges for deterring turbulent boundary layer air flow thereabout and an interior contour for promoting fiber spinning into a yarn.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the benefit of German patent applicationDE19910277.5, filed Mar. 9, 1999, herein incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a spinning rotor for open-end spinningmachines and, more particularly, to a spinning rotor which basicallycomprises a rotor cup having an annular wall portion defining a rotoropening, a bottom wall portion merging with the annular wall portion,and a mounting hub extending exteriorly from the bottom wall portion,with a rotor shaft affixed to the mounting hub coaxially with the rotorcup.

The requirement for greater and greater productivity has resulted in thedevelopment of current open-end rotor spinning machines operating atrotor speeds of well above 100,000 rpms. At such high speeds, specialrequirements arise as regards imbalance, bearing and stability (dangerof bursting) of the spinning rotors.

European Patent Document EP 0 099 490 B1 describes an open-end spinningrotor shaped in a non-cutting manner and with a fiber collector grooveto be used at high rotor speeds. In order to avoid the negative effectsof centrifugal forces occurring at high rotor speeds such as, e.g.,deformation or bursting of the spinning rotor, a bead is formed on theouter circumference of the edge of the rotor cup opening in order toincrease the strength. This reinforcement is intended to increase thebursting speed of the rotor.

German Patent Publication DE 197 34 637 A1 discloses a spinning rotor ofan open-end rotor spinning machine having a rotor shaft supported in thebearing slot of a support disk bearing arrangement and in an axialbearing which comprises magnetic bearing components. The spinning rotoris intended for rotor speeds of more than 100,000 rpms. This spinningrotor has a distinctly greater wall thickness in the area of the rotorgroove or in the area of the greatest outside diameter of the rotor thanin the area between the rotor groove and the opening edge. The stabilityof a body of rotation is increased with a greater wall thickness and anyoccurring tensions resulting from high speeds can be better distributed.Such embodiments are customary and are frequently used.

Spinning rotors which are reinforced or designed with a great wallthickness in the area of the greatest diameter have absolutelycontributed to a certain increase of the speed. However, furtherincreases in speed without losses of function or of safety can not beachieved with these known spinning rotors or can be achieved only in avery limited manner. In particular, problems of imbalance can beproduced in that a slight deviation of measurement occurring in thecourse of the manufacture of the spinning rotor results in the case ofrather large diameters or rather large masses in a greater imbalance.

SUMMARY OF THE INVENTION

It is accordingly an object of the present invention to improve spinningrotors for use at high speeds.

The invention achieves this objective by providing a spinning rotor foropen-end spinning machines which basically comprises a rotor cup havingan annular wall portion defining a rotor opening, a bottom wall portionmerging with the annular wall portion, and a mounting hub extendingexteriorly from the bottom wall portion, and a rotor shaft affixed tothe mounting hub coaxially with the rotor cup. The merger of the bottomand annular wall portions of the rotor cup defines thereat a maximumexterior diameter of the rotor cup and defines interiorly thereof arotor groove. The annular wall portion, the bottom wall portion and themounting hub are of different cross-sectional thicknesses and thecross-sectional thickness of the bottom wall portion increases from therotor groove to the mounting hub. In accordance with the presentinvention, the wall thickness at the maximum exterior diameter of therotor cup at the merger of the bottom and annular wall portions of therotor cup is between about 0.3 mm and about 1.2 mm, and the annular wallportion, the bottom wall portion and the mounting hub have anaerodynamic exterior contour free of edges for deterring turbulentboundary layer air flow thereabout while the annular wall portion andthe bottom wall portion have an interior contour for promoting fiberspinning into a yarn.

The described design of the present invention providing the rotor cupwith a slight wall thickness in the area of its greatest outsidediameter improves the distribution of mass and therewith the behavior athigh speeds of the rotor cup without inadmissibly weakening the rotorcup in this area. A reduction of weight is thereby possible which has anadvantageous effect on the operating qualities of the spinning rotor andon the consumption of energy.

Preferably, the exterior contour of the rotor cup from the rotor openingthrough the annular wall portion to the transition of the bottom wallportion into the mounting hub is configured to provide only convexcurvatures as viewed with respect to the axis of rotation of the rotorcup, which provides for favorable air flow about the rotor. Morespecifically, the outer contour of annular wall portion is a straightline from the rotor opening to the merger thereof with the bottom wallportion at which a convex curvature in the outer contour merges theannular wall portion with the bottom wall portion. In addition, theratio of the diameter of the rotor opening to the rotor depth betweenthe rotor opening and the rotor groove has a favorable effect on thesurrounding air flow during high speed operation of the rotor.

In order to optimize the compensation of mechanical tension forcesacting on the rotor cup and therewith improve the strength of the rotorcup, the wall thickness constantly increases from the rotor opening ofthe rotor cup to the rotor groove, the rotor groove has a radius in thegroove bottom which radius is at least 0.15 mm large, and furthermore,the ratio of the diameter of the rotor opening to the rotor depth isbetween about 2:1 and 5:1. The danger of a bursting of the rotor cup canbe thereby reduced and an increase of the bursting danger countered inspite of an increase in rotor speed.

A marking introduced by the removal of material, preferably by etchingor laser, from the exterior surface of the rotor cup simplifiesidentification during the manufacturing process as well as duringoperation and is more permanent than an application of colorant, whichfrequently becomes illegible or disappears entirely after a short periodof operation, e.g., due to contact or the action of friction. Theremoval of material for introducing the marking on the surface of thespinning rotor may serves at the same time to selectively balance out orcompensate the mass of the spinning rotor, thereby advantageously makingpossible an improved rotational behavior of the spinning rotor at highspeeds, and also saves expense and time in the manufacturing process ofthe spinning rotor.

In light of the teachings of the known state of the art that an increaseof the rotor wall thickness should be made in order to be able toincrease the rotational speeds without loss of function, it issurprising that the spinning rotor of the present invention with areduced wall thickness in the area of the greatest outside rotordiameter is better suited for high speeds of up to 150,000 rpms andpermits an increase in the speed of up to 25,000 rpms as a function ofthe nominal rotor diameter in comparison to known spinning rotors. Suchincreases in the rotor speeds by more than 20,000 rpms can be achievedespecially with nominal rotor diameters between 33 mm and 40 mm. Theincrease in speed made possible by this design of the spinning rotor inaccordance with the present invention permits a distinct increase inproductivity of the open-end spinning positions and of the open-endspinning machines and, therewith, an economical manufacture of yarn.

The reduction of the outside rotor diameter in conjunction with theformation of the exterior contour of the rotor cup to be free of sharpedges, depressions and protrusions, results in a significant reductionof the air resistance of the rotor cup and turbulence in the surroundingair flow at such high speeds. This can reduce the consumption of energyby up to 7 watts per spinning position. This results in open endspinning machines normally designed as multi-position textile machinesin a significant cost savings per machine, in the energy cost alone ofup to 2,000 DM per year.

It is also surprising that such advantageous effects can be achievedwith the relatively small change in the area of the greatest outsidediameter of the rotor cup in combination with the further features inaccordance with the invention. Improved balance properties of thespinning rotor of the invention result in improved operating behavior ofthe spinning rotors, drive elements and bearings and therewith ingreater operational safety and a higher degree of utilization. This alsobeings about an increase in productivity.

Further details, features and advantages of the invention will beunderstood from the following disclosure of a preferred embodiment ofthe invention in conjunction with the accompanying drawing figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view, partially in axial cross-section, ofa pinning rotor in accordance with a preferred embodiment of the presentinvention.

FIG. 2 is a detailed view of the spinning rotor of FIG. 1 at thelocation Z thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the accompanying drawings, FIG. 1 shows a spinningrotor 1 having a rotor cup 2 formed by a turning or like process from asolid block of appropriate material and fastened onto a rotor shaft 3.Alternatively, rotor cup 2 can also be formed into the desired shape bya casting process or in a non-cutting manner by a machining process. Therotor has a hub 4 for fastening of rotor cup 2 on rotor shaft 3. Theinterior area 6 of rotor cup 2 widens conically from an opening 5opposite the hub 4 and is defined by an inner side acting as a fiberglide surface 7 extending from the opening 5 to a rotor groove 9extending circumferentially about the rotor bottom wall portion 8 tofunction as a fiber collector groove. Fiber glide surface 7 and rotorgroove 9 form an annular edge 10 at their interface with one another.Rotor groove 9 is located at depth 13, measured from opening 5 to theedge 10. The ratio of the diameter of opening 5 to depth 13 isapproximately 2.8:1.

The annular wall portion 11 of rotor cup 2 between opening 5 and rotorgroove 9 is formed of a cross-sectional wall thickness which uniformlyincreases from opening 5 in the direction of rotor groove 9. Both theangular orientation of wall portion 11 at an acute angle of inclinationα to the axis of the rotor 1 and the length of this wall portion 11contribute to the favorable rotational behavior of the spinning rotor 1at high speeds. The outer contour of the rotor cup 2 is configured toprovide only convex curvatures in the axial direction from the rotoropening 5 along the annular and bottom wall portions 11, 8 and to thetransition from the bottom wall portion 8 into the hub 4. The shape andincreasing cross-sectional thickness of wall portion 11 results in agood distribution of the material tensions caused by the centrifugalforces and counteracts inadmissibly high tensions in the material. The 5stability of this spinning rotor 1 in combination with a design of fiberglide surface 7 and of rotor groove 9 which is favorable from thestandpoint of textile technology permits a yarn to be produced withoperational safety and uniformly high quality.

Rotor cup 2 has its greatest outside diameter as well as its minimumwall thickness 14 in the area of rotor groove 9, the wall thickness 14preferably being about 0.8 mm at this position. Rotor groove 9 has aV-shaped configuration with a radius 12, preferably of approximately 0.2mm, at the bottom of the groove.

FIG. 2 shows the above-described area of the greatest outside diameterof rotor cup 2 in a view enlarged in comparison to FIG. 1. Rotor groove9 which is designed to be V-shaped at an angle γ of approximately 40degrees and with radius 12 forms the inner wall surface of rotor cup 2at the position of the minimum wall thickness.

The wall thickness increases in the area of rotor bottom wall portion 8from rotor groove 9 in the direction of hub 4 at which rotor bottom wallportion 8 merges into hub 4. The entire outside contour of rotor cup 2is rounded and free of sharp edges, depressions or protrusions so as tofavorably enhance boundary-layer air flow and the aerodynamic behaviorof the rotor. The outer surface of rotor cup 2 carries marks for theidentification and marking of spinning rotor 1 in the form of picturemark 15 and inscription 16. Picture mark 15 and inscription 16 areproduced on the surface by the removal of material to a very low depthand covers a sufficient area to provide a balancing function on thespinning rotor 1. This can eliminate the otherwise customary grinding ofspinning rotors on their outside circumference and thus can eliminate anintervention into the outer contour of spinning rotor 1 which couldpossibly be unfavorable to boundary-layer air flow.

Further embodiments of spinning rotor 1 in accordance with the inventioncan be alternatively used. In particular, a plurality of shapingvariants of the inner and outer contour in wall portion 11 are possiblewithin the scope of the invention.

It will therefore be readily understood by those persons skilled in theart that the present invention is susceptible of broad utility andapplication. Many embodiments and adaptations of the present inventionother than those herein described, as well as many variations,modifications and equivalent arrangements, will be apparent from orreasonably suggested by the present invention and the foregoingdescription thereof, without departing from the substance or scope ofthe present invention. Accordingly, while the present invention has beendescribed herein in detail in relation to its preferred embodiment, itis to be understood that this disclosure is only illustrative andexemplary of the present invention and is made merely for purposes ofproviding a full and enabling disclosure of the invention. The foregoingdisclosure is not intended or to be construed to limit the presentinvention or otherwise to exclude any such other embodiments,adaptations, variations, modifications and equivalent arrangements, thepresent invention being limited only by the claims appended hereto andthe equivalents thereof.

1. A spinning rotor for open-end spinning machines, comprising: (a) arotor cup having, (i) an annular wall portion defining a rotor opening,(ii) a bottom wall portion merging with the annular wall portion todefine at the merger thereof a maximum exterior diameter of the rotorcup and in the interior thereof a rotor groove, the wall thickness atthe maximum exterior diameter of the rotor cup at the merger of thebottom and annular wall portions being between about 0.3 mm and lessthan 1.0 mm, and less than a wall thickness of the annular wall, and(iii) a mounting hub extending exteriorly from the bottom wall portion,the cross-sectional thickness of the bottom wall portion increasing fromthe rotor groove to the mounting hub; and (b) a rotor shaft affixed tothe mounting hub coaxially with the rotor cup.
 2. The spinning rotoraccording to claim 1, characterized in that the wall thickness at themaximum exterior diameter of the rotor cup at the merger of the bottomand annular wall portions of the rotor cup is between about 0.75 mm andabout 0.85 mm.
 3. The spinning rotor according to claim 1, characterizedin that an exterior contour of the rotor cup defined by the annular wallposition and bottom wall position comprises only convex curvatures. 4.The spinning rotor according to claim 1, characterized in that thecross-sectional thickness of the annular wall portion constantlyincreases from the rotor opening to the merger of the bottom and annularwall portions of the rotor cup.
 5. The spinning rotor according to claim1, characterized in that an exterior contour defined by the annular wallportion is a straight line from the rotor opening to the merger of thebottom and annular wall portions of the rotor cup.
 6. The spinning rotoraccording to claim 1, characterized in that the wall thickness at themaximum exterior diameter of the rotor cup at the merger of the bottomand annular wall portions of the rotor cup and exterior and interiorcontours of the rotor cup are designed to distribute the mass of therotor cup for accommodating tensions at the merger of the bottom andannular wall portions of the rotor cup at high rotational operatingspeeds of the rotor.
 7. The spinning rotor according to claim 1,characterized in that the ratio of the diameter of the rotor opening toa rotor depth between the rotor opening and the rotor groove is betweenabout 2:1 and about 5:1.
 8. The spinning rotor according to claim 1,characterized in that the rotor groove has a radius in a bottom of thegroove of at least about 0.15 mm.
 9. The spinning rotor according toclaim 1, characterized in that at least one marking is formed in anexterior contour of the rotor cup by removal of material from the rotorcup.
 10. The spinning rotor according to claim 9, characterized in thatthe removal of material for forming the marking is selectively made forbalancing the spinning rotor.
 11. The spinning rotor of claim 1, whereinthe cross-sectional thickness of the bottom wall portion continuallyincreases from the merger of the bottom wall portion to the mountinghub.
 12. The spinning rotor of claim 1, wherein indicia is formed on theexterior contour of the rotor cup by removal of material from the rotorcup forming a cavity therein.
 13. A spinning rotor for open-end spinningmachines, comprising: (a) a rotor cup having (i) an annular wall portiondefining a rotor opening, (ii) a bottom wall portion merging with theannular wall portion to define at the merger thereof a maximum exteriordiameter of the rotor cup and in the interior thereof a rotor groove,the wall thickness at the maximum exterior diameter of the rotor cup atthe merger of the bottom and annular wall portions being between about0.3 mm and no greater than 1.19 mm and less than a wall thickness of theannular wall, (iii) the wall thickness of the annular wall increasingtoward the merger, and (iv) a mounting hub extending exteriorly from thebottom wall portion, the cross-sectional thickness of the bottom wallportion continually increasing from the rotor groove to the mountinghub; and (b) a rotor shaft affixed to the mounting hub coaxially withthe rotor cup.
 14. The spinning rotor according to claim 13,characterized in that the wall thickness at the merger is between about0.75 mm and about 0.85 mm.
 15. The spinning rotor according to claim 13,characterized in that an exterior contour of the rotor cup defined bythe annular wall portion and bottom wall portion comprises only convexcurvatures.
 16. The spinning rotor according to claim 13, characterizedin that an exterior contour defined by the annular wall portion is astraight line from the rotor opening to the merger of the bottom andannular wall portions of the rotor cup.
 17. The spinning rotor accordingto claim 13, characterized in that the wall thickness at the merger andexterior and interior contours of the rotor cup are designed todistribute the mass of the rotor cup for accommodating tensions at themerger at high rotational operating speeds of the rotor.
 18. Thespinning rotor according to claim 13, characterized in that the ratio ofthe diameter of the rotor opening to a rotor depth between the rotoropening and the rotor groove is between about 2:1 and about 5:1.
 19. Thespinning rotor according to claim 13, characterized in that the rotorgroove has a radius in a bottom of the groove of at least about 0.15 mm.20. The spinning rotor according to claim 13, characterized in that atleast one marking is formed in an exterior contour of the rotor cup byremoval of material from the rotor cup.
 21. The spinning rotor accordingto claim 20, characterized in that the removal of material for formingthe marking is selectively made for balancing the spinning rotor. 22.The spinning rotor of claim 13, wherein indicia is formed on theexterior contour of the rotor cup by removal of material from the rotorcup forming a cavity therein.
 23. A spinning rotor for open-end spinningmachines, comprising: (a) a rotor cup having (i) an annular wall portiondefining a rotor opening, (ii) a bottom wall portion merging with theannular wall portion to define at the merger thereof a maximum exteriordiameter of the rotor cup and in the interior thereof a rotor groove,the wall thickness at the maximum exterior diameter of the rotor cup atthe merger of the bottom and annular wall portions being between about0.3 mm and no greater than 1.19 mm and less than a wall thickness of theannular wall, and (iii) a mounting hub extending exteriorly from thebottom wall portion; and (b) a rotor shaft affixed to the mounting hubcoaxially with the rotor cup.
 24. The spinning rotor according to claim23, characterized in that an exterior contour of the rotor cup definedby the annular wall portion and bottom wall portion comprises onlyconvex curvatures.
 25. The spinning rotor according to claim 23,characterized in that an exterior contour defined by the annular wallportion is a straight line from the rotor opening to the merger of thebottom and annular wall portions of the rotor cup.
 26. The spinningrotor according to claim 23, characterized in that the wall thickness atthe maximum exterior diameter of the rotor cup at the merger of thebottom and annular wall portions of the rotor cup and exterior andinterior contours of the rotor cup are designed to distribute the massof the rotor cup for accommodating tensions at the merger of the bottomand annular wall portions of the rotor cup at high rotational operatingspeeds of the rotor.
 27. The spinning rotor according to claim 23,characterized in that the ratio of the diameter of the rotor opening toa rotor depth between the rotor opening and the rotor groove is betweenabout 2:1 and about 5:1.
 28. The spinning rotor according to claim 23,characterized in that the rotor groove has a radius in a bottom of thegroove of at least about 0.15 mm.
 29. The spinning rotor according toclaim 23, characterized in that at least one marking is formed in anexterior contour of the rotor cup by removal of material from the rotorcup.
 30. The spinning rotor according to claim 29, characterized in thatthe removal of material for forming the marking is selectively made forbalancing the spinning rotor.
 31. The spinning rotor of claim 23,wherein indicia is formed on the exterior contour of the rotor cup byremoval of material from the rotor cup forming a cavity therein.
 32. Aspinning rotor for open-end spinning machines, comprising: (a) a rotorcup having (i) an annular wall portion defining a rotor opening, (ii) abottom wall portion merging with the annular wall portion to define atthe merger thereof a maximum exterior diameter of the rotor cup and inthe interior thereof a rotor groove, (iii) a wall thickness of theannular wall portion increasing toward the merger, (iv) a mounting hubextending exteriorly from the bottom wall portion, and (v) the rotorgroove producing a wall thickness at the merger less than the narrowestthickness of the bottom wall; and (b) a rotor shaft affixed to themounting hub coaxially with the rotor cup.
 33. The spinning rotoraccording to claim 32, characterized in that the wall thickness at themerger is between about 0.75 mm and about 0.85 mm.
 34. The spinningrotor according to claim 32, characterized in that an exterior contourof the rotor cup defined by the annular wall portion and bottom wallportion comprises only convex curvatures.
 35. The spinning rotoraccording to claim 32, characterized in that the cross-sectionalthickness of the annular wall portion constantly increases from therotor opening to the merger.
 36. The spinning rotor according to claim32, characterized in that an exterior contour defined by the annularwall portion is a straight line from the rotor opening to the merger ofthe bottom and annular wall portions of the rotor cup.
 37. The spinningrotor according to claim 32, characterized in that the wall thickness atthe merger and exterior and interior contours of the rotor cup aredesigned to distribute the mass of the rotor cup for accommodatingtensions at the merger at high rotational operating speeds of the rotor.38. The spinning rotor according to claim 32, characterized in that theratio of the diameter of the rotor opening to a rotor depth between therotor opening and the rotor groove is between about 2:1 and about 5:1.39. The spinning rotor according to claim 32, characterized in that therotor groove has a radius in a bottom of the groove of at least about0.15 mm.
 40. The spinning rotor according to claim 32, characterized inthat at least one marking is formed in an exterior contour of the rotorcup by removal of material from the rotor cup.
 41. The spinning rotoraccording to claim 40, characterized in that the removal of material forforming the marking is selectively made for balancing the spinningrotor.
 42. The spinning rotor of claim 32, wherein indicia is formed onthe exterior contour of the rotor cup by removal of material from therotor cup forming a cavity therein.